Stabilized liquid ozone



United States Patent 3,134,647 STABHJZED LIQUID OZONE John W. Churchill, Kenmore, N.Y., assignor to Olin Mathieson Chemical Corporation, a corporation of Virginia No Drawing. 'Filed Jan. 30, 1958, Ser. No. 712,272 3 Claims. (Cl. 23-222) This invention relates to liquid ozone which is stable under conditions of rapid evaporation.

Ozone, 0 molecular weight 48, is an unstable blue gas with a pungent characteristic odor and is generally encountered in dilute form in admixture with air or oxygen. It has a melting point of 191.1 C. and'a boiling point of -1l1.9 C. At ---111.9 C. ozone condenses to a dark blue liquid. Ozone is customarily handled as a gas or in admixture with liquid oxygen. It is used commercially in the purification of drinking water, as a powerful oxidant in both organic and inorganic reactions and in the treatment of industrial wastes. It is also used for the deodorization of air and sewage gases as well as for the preservation of foods in cold storage. More recently, liquefied ozone has found utility as an oxidant with rocket fuels. (See US. Patent 2,704,274 for a discussion in some detail of this use.) The handling of 7? liquid ozone during its preparation, storage, shipment and use has presented new problems since it is easily exploded as are concentrated ozone-oxygen mixtures (above about 15 weight percent ozone), in either the liquid or vapor state. These explosions may be initiated by minute amounts of catalysts or organic matter, shock, electric spark or sudden changes in temperature, pressure, etc. For example, any hot spots in lines, valves, etc., in a liquid could cause rapid evaporation of the liquid ozone resultingin an explosion.

It has now been found that liquid ozone can be rendered stable with respect to initiation of an explosion under rapid evaporation conditions by incorporating 5-chloro-2,4,6-trifiuoro pyrimidine therein. The amount of 5-chloro-2,4,6-trifluoro pyrimidine added to the ozone can vary widely but generally is from about 0.5 to 25 weight percent based on the ozone and preferably 15 to 25 Weight percent.

In order to evaluate the stability of the liquid ozone compositions of this invention a test procedure was devised which is as follows: A standard vacuum line is used to condense, concentrate and supply ozone'for the test. A mm. Pyrex tube, about 6 inches long and sealed .ofl at the bottom, is attached to the line after evacuation and ozone is vaporized from a storage trap and condensed into the test tube which is cooled in a liquid oxygen bath. The ozone is purified by evacuation ,to remove any oxygen resulting from decomposition during transfer. After adding nitrogen gas to the tube up to atmospheric pressure, it is manually removed from the oxygen bath and quickly placed in a water bath. The temperature of the latter determines the rate of boiling ozone handling system or any leaks in such a system a 3,134,647] Patented May 26 1964 and is the criterion which determines eifectiveness. Two types of results, upon immersion of the tube into the water bath, have been observed: an explosion, with shattering of the tube, or a rapid boiling with no attendant exploa sion. This test procedure was employed in the following examples:

Example I removed from the liquid oxygen bath and quickly placed in an ice-slush bath(0 C.) The tube exploded violently. Example [I 0.06 gram of 5-chloro-2,4,6-trifluoro pyrimidine Was placed in the tube and the tube was cooled to --183 C. by immersion in a liquid oxygen bath. Ozone, 0.3 gram, was then condensed on top of the 5-chloro-2,4,6-trifiuoro pyrimidine. After the tube was brought to atmospheric pressure by the addition of nitrogen gas, it was manually removed from the oxygen bath and quickly placed in a beaker of water maintained at 50 C. Upon immersion of the tube in the water, a rapid boiling of the ozone occurred with no explosion. It is apparent from this example that 5-chloro-2,4,6-trifluoro pyrimidine is effective in preventing an explosion when ozone is vigorously boiled.

- Example Ill The procedure of Example II was repeated using a water bath maintained at C. Upon immersion of the tube in the bath, the tube exploded violently.

I claim: 7

1. A liquid ozone composition consisting essentially of liquid ozone having incorporated therein 5-chloro- 2,4,6-trifluoro pyrimidine in an amount effective to stabilize the liquid ozone with respect to initiation of an explosion under rapid evaporation conditions.

'2. A'liquid ozone composition consisting essentially of liquid ozone and about 0.5 to 25 weight percent based on the ozone of 5-chloro-2,4,6-trifluoro pyrimidine.

3. A liquid ozone composition consisting essentially of liquid ozone and about 15 to 25 weight percent based on the ozone of 5-chloro-2,4,6-trifluoro pyrimidine.

OTHER REFERENCES Thorp: Bibliography of Ozone Technology, vol. 2,

Cook: Ind. and Eng. Chem, vol. 48, No. 4, pp. 736-741, April 1956. 

1. A LIQUID OZONE COMPOSITION CONSISTING ESSENTIALLY OF LIQUID OZONE HAVING INCORPORATED THEREIN 5-CHLORO2,4,6-TRIFLUORO PYRIMIDINE IN AN AMOUNT EFFECTIVE TO STABILIZE THE LIQUID OZONE WITH RESPECT TO INITIATION OF AN EXPLOSION UNDER RAPID EVAPORATION CONDITIONS. 